1 Field of the Invention
This invention relates to self calibration of an angle measuring apparatus for measuring the angle between two rotably mounted members. More particularly, it relates to self calibration of the measuring apparatus for measuring the angle between segments of a manipulator such as an articulated robot.
2 Description of the Prior Art
One prior art method of calibration is to position the segments of an articulated robot vertically. This is done visually and is quite inaccurate, being totally operator dependent. Any perceived deviation must be recorded and future readings compensated by the deviation.
Another method is to use bubble levels to place the robot members in either a horizontal or vertical position. Other positions may be achieved using a protractor equipped level. This method is subject to inaccuracies in the leveling surface on the robot, the accuracy of the level itself and the operator's skill.
A third method is to place alignment marks on adjacent surfaces of the segments of a robot and to visually align these marks. This method is subject to operator error in aligning the marks visually. Also, the width of the marks is a limiting factor in the possible resolution. Further, a manufacturing error associated with placing these marks on the joint members is also a source of error.
The present invention overcomes the drawbacks of these prior art methods described.